Lots of people have kept a rooster with a small group of hens. Sometimes there is no problems, sometimes there are small problems (broken feathers, which tend to bother people worse than hens) and sometimes they are nightmares.
AArt generally makes this point, if you are keeping a rooster, you need a plan that you can implement NOW with what to do if the rooster does not work.
A couple of points, a rooster chick is generally your favorite, he is so brave, so rash, so friendly. In a flock mate only flock, where all the birds are the same age, he will rapidly get much bigger than the pullets, sexually mature before them, and often times become quite aggressive. This forum is loaded with posts where the darling became a nightmare in an instant. He probably didn't, but inexperienced people do not alway pick up on the signals.
I prefer and think you get much better roosters when you raise roosters within a multi-generational flock by people who have experience with chickens. However, recently I have read a post, where it was recommended that if you pull the rooster at about 14 weeks and wait until the pullets are laying, it works much better. Juvenile roosters often terrorize the pullets when they are ready and the girls are not.
If you are going to have a rooster, you need a sharp knife, in case it does not work, or an area to separate the bird. If you have small young children be very aware that roosters generally attack children first, and roosters have ruined the whole chicken experience for a lot of kids.
Good luck, and be aware
Mrs K